Red imported fire ant is insect pest which particularly causes enormous damage to agricultural crops in the U.S.A. As the use of agricultural chemicals has been restricted or even prohibited in recent years, it has been strongly desired to develop a new method of controlling this insect.
Controlling methods using various biologically active substances have been studied, and the use of pheromones has especially attracted attention. In particular, since the queen recognition pheromone is a pheromone by which worker ants recognize the queen, the use of such a queen recognition pheromone will permit an effective control of this insect species.
The queen recognition pheromone is composed mainly of the following three components: ##STR1##
The compound (b) which is called invictolide is very difficult to synthesize stereoselectively since it contains four asymmetric carbons. The only prior report on its synthesis is Ziegler et al., Tetrahedron Letters, 27, 1229 (1986). However, this prior method of synthesis requires a number of steps and is difficult to employ industrially. Moreover, the invictolide obtained by this method has a low optical purity.